We're talking about using it with the output set to 5V. Then the maximum power is 15W. Even so, that depends on unlimited input current from the 12V. If you can short or abuse the output in some way as to cause injury, you can surely achieve the same result with the input voltage.
Really, the possibility of an injury specifically caused by a module like that, is extremely slim. It's the unexpected problems that you have to look out for - like young children swallowing it or cutting your fingers on sharp PCB edges... 